in function parameters, you don't need var keyword. Parameters are passed by
immutable reference by default, only when you want to change the argument in
the function you need the var declaration.
type
animal = object of RootObj
dog = object of animal
cat = object of animal
method say(self: animal) = discard
method say(self: dog) = echo "woof!"
method say(self: cat) = echo "meow?"
proc make_noise(a: animal) =
a.say; a.say; a.say
proc main =
let d = dog()
let c = cat
d.make_noise
c.make_noise
main()
